Horsham is a home rule municipality in Montgomery County, Pennsylvania, United States. The population was 14,842 at the 2010 census. Horsham is located entirely within Horsham Township, and it is home to the Horsham Air Guard Station at the former site of Naval Air Station Joint Reserve Base Willow Grove. Horsham is located 34 miles (55 km) southeast of Allentown and 16 miles (26 km) north of Philadelphia.